This invention relates generally to devices for implementing a ground connection between a metallic sheath of a cable and a common ground point. More particularly, the present invention relates generally to devices for providing a water-proof ground connection between a metallic sheath of a cable and a common ground point.
Buried telecommunications cables often utilize a distribution pedestal for housing cable ends and splices. These pedestals provide easy access to the cable ends without excavation of the buried cables for splice installations, maintenance and troubleshooting. However, such pedestals are not a closed environment and rain run-off or other ground water may enter the splice. This moisture will contribute to the corrosion of the copper conductors and metallic sheath leading to a degradation of the mechanical integrity and the electrical characteristics of the cable. Generally, the splices are made watertight to prevent the introduction of water. The splices may be made watertight by encapsulating or flooding the splice area with a urethane or gel compound. Alternatively, the splice bundle may be enclosed in a heat shrinkable enclosure.
If the cable includes a metallic sheath, the sheath must be electrically bonded to the pedestal housing. The housing, in turn, should be grounded. Consequently, a grounding conductor, typically a number 6 AWG conductor, must exit the encapsulated/housed splice for connection to the pedestal housing. In geographic areas which are subject to ground freeze/thaw cycles, there is relative movement between the pedestal housing and the cables since the cables are usually buried below the frost line and the pedestal housing is buried at least partially above the frost line. If the ground connection is not sufficiently flexible to accommodate such relative movement or roadside vibration, the watertight seal will be jeopardized. A solid number 6 AWG conductor is relatively stiff and is too inflexible to properly accommodate relative motion between the pedestal housing and the splice. If a stranded number 6 AWG conductor is used, moisture can wick into the space between the individual conductors and enter the splice.
One conventional grounding device mounts a solid number 6 AWG conductor to a stranded number 6 AWG conductor via a butt splice. The solid conductor is mounted to the cable sheath and extends out of the encapsulated/housed splice. The stranded conductor provides sufficient flexibility to allow relative movement between the splice and the pedestal housing. Although both conductors are number 6 AWG, the outside diameter of the stranded conductor is greater than that of the solid conductor. Typically, a connector having one end which is sleeved to reduce the inside diameter is used to ensure that connector is properly crimped. Such connectors are relatively expensive. In addition, the assembly worker must identify which end of the connector has been sleeved and orient the connector to insert each conductor into the proper end of the connector. Consequently, it takes a relatively long time to assemble each grounding device even though the device has a relatively simple design.
In addition to the difficulty of properly connecting two different diameter conductors, crimped connections are subject to degradation of their mechanical and electrical properties if they do not provide a "gas tight" connection. A crimped wire connection is "gas tight" if all of the individual conductors of a stranded conductor are compressed together leaving no voids for air and moisture to enter. For a solid conductor, the connection is "gas tight" if the conductor cannot rotate within the connector. If the connection is not "gas tight" moisture will enter the connection causing corrosion which degrades the mechanical connection and electrical properties of the connection. It is especially difficult to insure that both connections in a butt splice are "gas tight" when a solid conductor is joined to a stranded conductor and the conductors have different diameters.